Goodness, the idea of this hardware project resulting in a Contiki-like environment for an Atmos or two just boggles my mind. Please let me know if there is anything I can do to assist as an early user (Telestrat,Atmos,Oric-1 at the ready!)

The idea of having a full DOS with domain over 512Megs of Oric .DSK's on a single SD just excites me to no end.

I vote for a hardware implementation, however, which requires as little software moderation as possible - if the Microdisc can be emulated to work on a vanilla Oric, would be best of all imho.

On my side, I have two other questions:
- How expensive/difficult is it to have 8 banks of RAM versus just 2 banks. I guess it's a bigger memory chip with more pins, is that much more problematic to use? If not, why not 16, 32, 64 pages??? (just to push the cork)

six years after, i found this post

Twilighte card handles 7*16KB of rom bank like telestrat. But it can also handles 7 banks of RAM and almost 32 banks too because there is a 512KB SRAM on the board. It's not activated in the CPLD, mainly because, it's a bit slow to manage it with software code.

For example, for Orix (telemon initially), keyboard buffer is in RAM overlay. When we read a key, we have to switch to the ram overlay for each keys read.

Well, it's possible on Twilighte card, but as i said it's not activated because i would like to have a mmu instead, if i can handle it on the oric !

/me still thinks that having joystick and mouse ports could be awesome, would allow us to make other types of games.

Done also on twilighte card (joysticks and mouse). 3 ways to have mouse on the card :

1) Joystick port : plug a amiga mouse or atari mouse, and driver must be written
2) on joysticks port : with an usb to db9 converter (tom2 for example) and plug a usb mouse : driver must be written too
3) plug the usb mouse in usb port, and the hardware will return delta X & deltaY from the last access to the chip, (coordinates must be read from page 3) Driver must be written too

Done also on twilighte card (joysticks and mouse). 3 ways to have mouse on the card :

1) Joystick port : plug a amiga mouse or atari mouse, and driver must be written

Since the Amiga and Atari mice use quadrature encoded signals to send movement information I assume that this means that there must be code on the Oric which constantly listens to the DB9 inputs and does the quadrature decoding manually? On first thought this looks like this could consume quite a large bit of CPU time.
The Amiga uses dedicated hardware which decodes the quadrature signals and increments corresponding dedicated movement counters (one for each DB9 port) and I assume the Atari ST is the same but that would have to be done entirely in software on the Oric which would be quite expensive.

3) plug the usb mouse in usb port, and the hardware will return delta X & deltaY from the last access to the chip, (coordinates must be read from page 3) Driver must be written too

This option looks like it would be much lighter on the Oric since the deltaX/Y would be read directly by the machine and only when needed. In my opinion, unless there is dedicated quadrature decoding hardware on the Twilighte board, this is the most interesting option of the three since it keeps mouse movement querying as simple as possible for the Oric.

3) plug the usb mouse in usb port, and the hardware will return delta X & deltaY from the last access to the chip, (coordinates must be read from page 3) Driver must be written too

This option looks like it would be much lighter on the Oric since the deltaX/Y would be read directly by the machine and only when needed. In my opinion, unless there is dedicated quadrature decoding hardware on the Twilighte board, this is the most interesting option of the three since it keeps mouse movement querying as simple as possible for the Oric.

Not only that, but if done smartly it would also be compatible with some existing software that handled light pens and graphical tablet (graphiscope).
Both of these devices provided with simple registers to read in page 3.

And yes, the Atari ST has a dedicated 8 bit cpu just for the keyboard/joystick/mouse handling, with a custom serial port protocol to transmit information.